In the process of shipping an item from one location to another, protective packaging material is often placed in the shipping container to fill any voids and/or to cushion the item during the shipping process. Some commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to perform adequately as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and plastic foam peanuts is their affect on our environment. Quite simply, these plastic packaging materials are not biodegradable, and therefore they cannot avoid further multiplying our planet's already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
The foregoing and other disadvantages of conventional plastic packaging materials have made paper protective packaging material a popular alternative. Paper is biodegradable, recyclable and composed of a renewable resource, making it an environmentally responsible choice for conscientious shippers.
While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a relatively low density pad-like cushioning or dunnage product. This conversion may be accomplished by a cushioning conversion machine, such as that disclosed in commonly assigned U.S. Pat. No. 5,123,889. The conversion machine disclosed in U.S. Pat. No. 5,123,889 converts sheet stock material, such as paper in multi-ply form, into relatively low density pads. Specifically, the machine converts this stock material into a continuous unconnected strip having lateral pillow portions separated by a thin central band. This strip is connected as by coining along its central band to form a coined strip which is cut into sections, or pads, of a desired length. The stock material preferably consists of three superimposed webs or layers of biodegradable, recyclable and reusable thirty-pound Kraft paper rolled onto a hollow cylindrical tube. A thirty-inch wide roll of this paper, which is approximately 450 feet long, weighs about 35 pounds and will provide cushioning equal to approximately sixty cubic feet of plastic foam peanuts while at the same time requiring less than one-thirtieth the storage space.
The conversion machines known in the prior art, including the one shown in U.S. Pat. No. 5,123,889, have used a freely rotating roll from which the stock material to be converted is fed by means of the same mechanism that advances the material through the forming portion of the machine. Specifically a pair of gears that have performed a connecting operation have been used to advance the material being converted. These gears stop and start their rotation during the conversion process, and this results in the need to accelerate the stock roll every time the gears start, with resulting changes in the tension of material being fed through the conversion machine. These changes in the tension of the material can affect the quality of the dunnage product being produced.
Also, when the conversion process is stopped, the rotational inertia of the stock roll can cause the stock roll to overrun and form a loose loop of material at the supply end of the conversion machine. When the conversion process is resumed, initially the material will be at a relatively low tension until the loose loop of material is taken up, at which point the tension on the paper will rapidly increase, almost instantaneously, to a relatively high level until the stock roll accelerates to match the feed rate through the machine. This quick change in tension can cause the material to tear, as well as degrade the quality of the dunnage product being produced.
Another problem that arises from time-to-time in cushioning conversion machines of the aforesaid type are machine jams in the region of the severing assembly. A commonly used severing assembly includes a moving blade which travels between a retracted rest position and an extended full cut position. More specifically, a cutting cycle of the blade includes a cutting stroke during which the formed strip of dunnage is cut and a return stroke during which the blade returns to the rest position. During the cutting stroke, the moving blade unit travels across the dunnage outlet opening and cuts the dunnage strip into a cut section, or pad, of a desired length.
Although this cutting assembly is adequate to perform the cutting function, in certain situations the cut end of the continuous dunnage strip remaining in the cushioning conversion machine may interfere with the return stroke of the moving blade. If this interference is severe, the movement of the blade or subsequent feeding of the dunnage strip may be adversely affected to a point that a machine jam occurs. Although serious jams may be rare, they can result in mechanical damage. Misalignment of the trailing end of a cut pad has been previously addressed in U.S. Pat. No. 5,569,146. This patent discloses a cutting/aligning assembly that includes an automatic alignment device which automatically “re-aligns” the cut section with the outlet opening and a post-cutting guide chute during the return stroke of the moving blade unit. The alignment device seeks to insure a smooth transition for the cut section from the outlet opening through the post-cutting constraining assembly.